Many of semiconductor device testing apparatus (commonly called as IC tester) for measuring the electrical characteristics of semiconductor devices to be tested (i.e. devices under test) by applying signals of a predetermined test pattern to the devices have a semiconductor device transporting and handling or processing apparatus (as will be referred to as handler) integrally mounted thereto. One of the measurement items for the electric characteristics of a semiconductor device, for instance, a semiconductor integrated circuit (hereinafter referred to as IC) which is a typical of semiconductor devices is the temperature characteristic. In order to measure the temperature characteristic of a device, it is required to heat the device under test by applying temperature to it in a preheating stage disposed within a constant temperature or thermostatic chamber of the handler maintained at a predetermined temperature. In this case, to shorten the test time, it is needed to heat a number of devices under test introduced and loaded onto the preheating stage in such a manner that they will reach, uniformly and in a short time, a predetermined temperature at which they are to be measured for their temperature characteristics. For the benefit of simplifying the description, the following description will be discussed with reference to ICs which are typical of semiconductor devices.
FIGS. 1 and 2 illustrate the construction of a prior art constant temperature chamber in the handler in which a preheating stage is provided for applying a temperature or hear to an IC to be measured until it reaches a predetermined set temperature in order to measure the temperature characteristic of it. As shown, the constant temperature chamber 11 is enclosed by thermal insulation walls 4 each having dimensions of about 600 mm.times.600 mm within which a rotary stage 5 (commonly called turntable) for preheating ICs is mounted. Attached to the top of the rotary stage 5 is a change kit 12 (which may be interchanged depending on the type, configuration, etc. of semiconductor devices to be tested) in the form of an annular disk onto which ICs 10 to be tested are introduced and loaded to be heated to a predetermined set temperature.
Shown in FIGS. 1 and 2 is the construction of the prior art constant temperature chamber 11 including the rotary stage 5 for preheating. The rotary stage 5 is rotated at a predetermined speed by means of a rotary shaft 9 secured thereto at the center thereof which is rotatively driven from a drive source (not shown) located above the chamber 11. Mounted exteriorly below the bottom wall of the chamber is a fan motor 1 for rotatively driving an axial-flow fan or axial blower 2 positioned inside of the chamber 11 at the bottom thereof. The arrangement is such that rotation of the axial-flow fan 2 directs the heat from a spiral heater 3 located above the fan 2 toward the overlying rotary stage 5. The rotary stage 5 includes a central perforated plate 6 having a number of through-apertures extending axially of the rotary shaft 9 (in upward-downward direction as viewed in FIG. 1). ICs 10 to be tested (commonly called DUT) are loaded on the change kit 12 outside of the perforated plate 6. It is thus to be understood that circulating gas (air) flows 7 as indicated by arrows occur in which the heated gas from the heater 3 is forced by rotation of the axial-flow fan 2 to pass through the perforated plate 6 and be directed towards the ICs 10 under test resting on the rotary stage 5 at its outer section, followed by passing around the outer periphery of the rotary stage 5 back to the axial-flow fan 2. The ICs 10 under test loaded on the rotary stage 5 are thereby heated up to a preset temperature.
Upon reaching the preset temperature, the ICs under test are removed from the rotary stage 5 and conveyed to a testing section not shown for effecting tests (measurements) within the constant temperature chamber 11 to be subjected to the necessary testing.
With the constant temperature chamber 11 having the built-in rotary stage 5 constructed according to the prior art as described above, there also occur gas streams flowing laterally outwardly from the axial-flow fan 2 as indicated by arrows in FIG. 1, resulting in non-uniform temperature rise among the ICs 10 under test resting on the outer section of the rotary stage 5. That is, increases in temperature are uneven depending upon the location on the rotary stage 5, resulting in being undesirably unable to uniformly raise the temperature of all of the ICs under test. This has led to the disadvantage that a considerably long time is required before all of the ICs under test are heated up to and stabilized at the preset temperature.
When ICs under test are to be measured for their temperature characteristics, it is required that ICs to be tested be introduced and loaded onto the outer section of the rotary stage 5 for preheating just before the measurement and be subjected to uniform heat so that all of the ICs are uniformly heated up. In addition, to reduce the test time, it is necessary, as indicated above, to heat all of the ICs to be tested loaded on the rotary stage up to a predetermined temperature in a uniform and reliable manner and yet in a short time. There is thus a need for a constant temperature chamber of such a construction as to enable the axial-flow fan 2 to provide its characteristic as much as possible in applying the heat from the heater to the ICs to be tested.